1. Field of Invention
This invention is concerned with a pharmaceutical dosage form. More particularly, the instant invention involves a pharmaceutical suspension of cefazolin for parenteral administration.
2. Prior Art
The cephalosporins constitute an important class of semisynthetic antibiotics that have proved highly useful in treating bacterial infections in man. Cefazolin is one of this class. Some of the cephalosporins are administered orally, some parenterally, and others are useful both orally and parenterally. Presently, cefazolin is administered parenterally for a variety of respiratory, genito-urinary and other infections. It is particularly effective against Staphylococcus aureus.
Currently, cefazolin is administered as a solution of its sodium salt; cefazolin sodium being very soluble in water. One of the significant problems with the administration of a cefazolin sodium solution is the pain and irritation experienced by the patient at the site of the injection. Moreover, the blood levels which develop after an injection of cefazolin sodium are of relatively short duration, requiring frequent injections to maintain a therapeutic cefazolin blood level.
Cefazolin, an acid in its unmodified form, has a relatively low solubility in water; something in the order of 3.0 mg/ml. And, a number of antibiotics having low water solubilities; namely penicillins such as the procaine and the benzathine forms, have been prepared as pharmaceutically acceptable suspensions for parenteral administration (I.M.). A variety of formulations have been used over the past three decades. All have been preparations in which finely divided particles have been suspended in a vehicle comprised of water and one or more of wetting agents, suspending agents, emulsifiers, viscosity adjusting agents, preservatives, buffers, and the like. Generally, these adjuncts have been present in various combinations and widely diverse concentrations. All these pharmaceutical aids (a U.S.P. description) have the approval of the United States Pharmacopeia, National Formulary, Food Chemicals Codex, or the Food and Drug Administration after the safety has been established for the purpose.
Accordingly, it is an object of this invention to provide a pharmaceutical suspension of cefazolin for parenteral administration utilizing pharmaceutically approved ingredients that induce a minimum of pain and irritation when injected intramuscularly.
It is another object of this invention to provide a cefazolin suspension that induces a prolongation of therapeutic blood levels on intramuscular injection.